1. Field
The present disclosure relates to compositions, kits, and methods for detecting and analyzing vesicles.
2. Description of the Related Art
Microvesicles are small membrane-bound vesicles that exist in or are secreted from various types of cells. Microvesicles include (i) exosomes, membraneous vesicles 30 to 100 nm in diameter that are secreted by a wide range of mammalian cell types, (ii) ectosomes (shedding microvesicles (SMVs)), large membranous vesicles 50 to 1000 nm in diameter that are released directly from plasma membranes, and (iii) apoptotic blebs: vesicles 50 to 5000 nm in diameter that are secreted from dying cells.
Using an electron microscope, it has been observed that exosomes are not directly released from plasma membranes, but rather originate from specific intracellular regions called multivesicular bodies (MVBs), which fuse with the plasma membrane and are then released into the extracellular environment as exosomes. Exosomes are secreted from various different cell types under both normal and pathologic states. Erythrocytes, various types of immunologic cells (including B-lymphocytes, T-lymphocytes, dendritic cells, platelets, and macrophages), and tumor cells produce and secrete exosomes. Microvesicles may contain microRNAs (miRNAs), which may be used to diagnose various conditions, including cancer.
Existing methods of detecting and characterizing microvesicles are performed by immuno-capturing microvesicles and then detecting a protein in the microvesicles using a labeled antibody. However, such methods may cause a bias due to masking of antibody recognition sites by changes in a protein structure, microvesicle heterogeneity, protein interactions, etc. In addition, detection results may be inaccurate due to contamination by external proteins, for example, secreted or fragmented proteins. Furthermore, many existing methods require a complicated process, a high-cost apparatus, or a large sample volume.
Therefore, there is a need for improved methods of detecting and quantifying microvesicles, analyzing microvesicle proteins, glycoproteins, or lipids, and screening ligands that have binding affinity for microvesicles.